1. Field of Technology
The present invention relates generally to a heat exchanger for application to an apparatus for collecting heat from exhaust gas of such a machine as to produce noise when operating, and more particularly to thermal exchanger which can also attain silencing noise from exhaust gas of the machine when operating.
2. Description of the Prior Art
Recently, a heat pump apparatus driven by an internal combustion engine has been combined with a heat exchanger for collecting heat from its exhaust gas to heat liquid such as water. In such combined heat pump and heat exchanging apparatus, collection with high efficiency of heat from the exhaust gas, and suppressing of noise of the exhaust gas are important problems to be solved. Hitherto, apparatus for collecting heat from the exhaust gas and apparatus for suppressing noise of the exhaust gas are provided as separate apparatuses, and accordingly not only the space occupied by the apparatuses was large, but also noise of exhaust gas and noise transmitted through outer shell of a muffler were considerable. Furthermore, the usual resonance type muffler used for suppressing low frequency components of exhaust noise of the internal combustion engine is effective only for a predetermined revolution speed of the engine. Furthermore, in view of heat exchange efficiency, the conventional heat exchanger usually has an expanded heat exchanging surface, such as fins in the flow path of the exhaust gas, or only comprises a simple plate partition between the liquid and gas. However, such configurations of heat exchanger cannot satisfactorily exchange heat by utilizing the pulsive flow of the exhaust gas. And furthermore, there is a problem that when high efficiency of heat recovery is intended the exhaust gas is condensed, and in case of the exhaust gas of the internal combustion engine which includes strong acid resulting from nitrogen oxides in the exhaust gas is liable to corrode the fins or plates, thereby deteriorating the heat exchanging performance of these components and also deteriorating efficiency of the heat exchanger by choking of the flow-path of the exhaust gas by the corroded substances.